1. Field of the Invention
The present invention relates to a lens driving device for focusing or adjusting a focus (zoom) of a digital camera, a portable telephone with a camera, or a disk reader, and electronic equipment including the same.
2. Description of the Related Art
Conventionally, in electronic equipment such as a digital camera, a portable telephone with a camera, or a disk reader targeting a next-generation optical disk, focusing or focus adjustment has generally been performed by using a lens driving device to adjust a lens position.
Various types of lens driving devices have been available, a representative one of which adjusts a lens position by using a nut and a lead screw. The lens driving device of this type typically includes a lead screw rotated by a motor, a nut threadingly engaged with the lead screw, a lens frame provided to move back and forth along a guide shaft disposed in an optical axis direction in its abutting state on the nut and to fix a lens, and a rotation regulation unit for regulating rotation of the nut (e.g., refer to JP 2006-98464 A and U.S. Pat. No. 5,987,262).
In the lens driving device thus configured, when the motor is driven to rotate the lead screw, the nut may rotate in accordance therewith. However, the nut moves back and forth in an axial direction of the lead screw because its rotation is regulated by the rotation regulation unit. The lens frame abutting the nut accordingly moves back and forth together with the nut along the guide shaft. Thus, the lens fixed to the lens frame can be moved back and forth in the optical axis direction. As a result, the position of the lens can be adjusted to enable focusing or focus adjustment.
However, the conventional lens driving device still has the following problems.
First, in order to move the nut back and forth through rotating the lead screw, it is necessary to regulate the rotation of the nut by the rotation regulation unit. If rotation regulation is uncertain, the nut is rotated in accordance with rotation of the lead screw, disabling back-and-forth movement of the nut. Thus, when the lens driving device is assembled, combination of the nut with the rotation regulation unit has to be ensured to surely regulate rotation of the nut.
Conventionally, however, no adequate consideration has been given to combination of the nut with the rotation regulation unit. Thus, during assembling, the nut has had to be blindly combined with the rotation regulation unit through a peephole formed in a module, or simultaneously combined while regulating the direction of the nut by using a special jig. As a result, the assembling has become complex and difficult, and assembling failures or damages of various components have resulted in increasing costs.
Additionally, to realize further downsizing of the electronic equipment on which the lens driving device is mounted, there is a demand for downsizing of the nut itself. There is also a demand for improvement of assembling performance to achieve much higher manufacturing efficiency simultaneously with downsizing. In the conventional lens driving device, however, the aforementioned reason has made it difficult to meet such needs.